Decatopecten plica ( Linnaeus, 1758 )

Dijkstra, H. H. & Kilburn, R. N., 2001, The family Pectinidae in South Africa and Mozambique (Mollusca: Bivalvia: Pectinoidea), African Invertebrates 42, pp. 263-321 : 277-278

Decatopecten plica ( Linnaeus, 1758)

(Figs 12–13)

Ostrea plica Linnaeus, 1758: 696 , no. 162; Dijkstra, 1999: 404, figs 2 A-D (lectotype). Type locality: ‘ O. Indico’, restricted to ‘Amboina (Ambon, Maluku, Indonesia) by Iredale (1939: 361).

Decatopecten plica ; Dijkstra & Knudsen, 1998: 55, pl. 9, figs 40–41 (references, synonymy, type data, distribution, discussion).

Pallium striatum Schumacher, 1817: 120 . Type locality: not given, although ‘Canton’ (Guangzhou, Guangdong, China) on type labels.

Decatopecten striatus ; Kira, 1962: 139, pl. 50, fig. 6.

Decatopecten striatum ; Bernard, Cai & Morton, 1993: 51.

Pecten velutinus G. B. Sowerby 2nd, 1842: 63, pl. 13, fig. 31; Reeve, 1852: pl. 2, fig. 12; Küster & Kobelt, 1888: 95, pl. 26, figs 2–3; Rombouts, 1991: 37, pl. 13, fig. 11. Type locality: ‘Macassar’ (Ujung Pandang, Sulawesi, Indonesia).

Pecten subplicatus G. B. Sowerby 2nd, 1842: 64, pl. 13, fig. 37, pl. 14, figs 72–73, 81; Reeve, 1852: pl. 3, figs 17a–b; Dunker, 1882: 242; Küster & Kobelt, 1888: 157, pl. 44, figs 3–5; Rombouts, 1991: 37, pl. 13, fig. 10. Type locality: ‘Amboina’ ( Ambon, Maluku, Indonesia).

Pecten (Pallium) subplicatus ; Dautzenberg & Bavay, 1912: 26 (synonymy).

Pecten strangei Reeve, 1852 : pl. 4, fig. 22; idem, 1853: pl. 32, fig.148; Küster & Kobelt,1888: 169, pl. 47, fig. 2. Type locality: Moreton Bay, Queensland.

Decatopecten strangei ; Iredale, 1939: 361; Lamprell & Whitehead,1992: sp. 68, pl. 12, fig. 68.

Decadopecten (Decadopecten) strangei ; Rombouts, 1991: 37, pl. 13, figs 9–9a.

Comptopallium strangei ; Abbott & Dance, 1982: 307, fig.

Pecten (Nodipecten) noduliferus (in part non Sowerby, 1842); Boshoff, 1965: 133, pl. 13, fig. 2.

Description: Shell thick, height to 55 mm, but most adults 30–35 mm, elongate to suborbicular, nearly equivalve, equilateral, auricles small and subequal, umbonal angle ca. 85–95°. Both valves strongly convex to more compressed, with prominent radial plicae (3–5, usually 3) and smaller lateral ribs (2–3), both plicae and their intervals radial striated. Microsculpture of close-set commarginal lamellae.Auricles with several radial riblets (8–14) and microscopic commarginal lamellae. Hinge small and straight.

Byssal fasciole absent, byssal notch narrow. Active ctenolium with a few small teeth

(1–3) on suture, sometimes absent. Resilifer elongate, triangular.Auricular crura strongly developed, resilial teeth weak or absent. Inner surface slightly plicated. Colour variable, 12 13

Figs 12–13. Decatopecten plica ( Linnaeus, 1758) : NMSA G4998, Macoque, Mozambique, pv, H 39.8 x 36.6 mm. 12. LV exterior. 13. RV exterior.

cream, yellow, orange or brown with lighter or darker markings, occasionally uniform in colour; RV paler than LV.

Type material: O. plica : syntypes in LSL and UUZM (not registered) , lectotype in LSL (designated Dijkstra 1999) . P. striatum : lectotype ZMUC BIV-59 herein designated; paralectotype ZMUC BIV-60. P. velutinus : lectotype BMNH 1996405 / 1 herein designated; 2 paralectotypes BMNH 1996405 / 2-3. P. subplicatus : type material not present in BMNH (K. Way and J. Pickering pers. comm.) . P. strangei : lectotype BMNH 1950.11 . 14.74 herein designated, 2 paralectotypes BMNH 1950.11.14.75–76.

Regional data (all NMSA, selected records only): MOZAMBIQUE: Macoque, beachdrift (G4998: E. Roscoe); Santa Carolina Is., Bazaruto Archipelago, dead on sandbank (K2281: E. Roscoe); Inhaca Is. (4488: P. H. Boshoff). SOUTH AFRICA (all NMDP, unless otherwise stated): Zululand: between Bhanga Neck and Kosi Bay, off outer edge of No. 13 reef, ca. 34 m, sand, live (D9814: D. Herbert et al.); NE of Kosi Bay, 42–44 m, fine sand, dead (S5309); off Kosi Bay, dredged, dead, 40 m, shell rubble, dead (D7973); same loc., 45 m, fine muddy sand, dead (D6039); same loc., 47 m, dead coral, sponges, large algae, living (D6133); SE of Kosi Bay, 40 m, shell rubble (D8138); off Lala Nek, 70 and 72 m, dead (S6625, S7011); SE of Rocktail Bay, 60 m, dead (S5221); off Sodwana, 49–53 m, sand, dead (S4728).

Distribution: Throughout tropical Indo-Pacific, except Hawaii and Polynesia, south-western limit northern Zululand.

Habitat: Living free between coral rubble on muddy or clean sand bottoms at littoral to sublittoral depths.

Remarks: D. plica shows extreme polymorphic variability in various characters, namely valve convexity (from inflated to compressed), strength of radial plicae (strong to weakly developed), number of plicae (3–5, with 2 or 3 lateral ribs) and coloration. Specimens from Japan (in literature usually identified as D. striatus ) and Australia (often identified as D. strangei ) may be considered as ecomorphs or local forms of D. pli c a. Samples from Mozambique and South Africa resemble the type material of D. pli c a.